Supplementary Material 1

Transcription

1 Supplementary Material 1 Supplemental Material Table 1: Details for Table 1 of the paper. Ichnotaxon Biological Counterpart (Trackmaker) Ameghinichnus advanced synapsid, possibly trithelodontid (1) Rhynchosauroides hyperbates lepidosauromorph or primitive archosauromorph (2,3) Rhynchosauroides spp. lepidosauromorphs (2,3) Chirotherium lulli crurotarsan, possibly aetosaurid (4) Procolophonichnium procolophonid parareptile (5) Gwyneddichnium tanystropheid (6) Apatopus phytosaur (3) Brachychirotherium parvum rauisuchian crurotarsan (7) new taxon B crurotarsan, possibly crocodylomorph (8) Batrachopus deweyii crocodylomorph (9) Batrachopus gracilis crocodylomorph (9) unnamed dinosaurian genus 1 unknown dinosaur, perhaps herrerasaurid Otozoum prosauropod dinosaurs (10,11) Grallator small theropod dinosaur (12) Anchisauripus small to medium sized theropod dinosaur (12) Eubrontes giganteus large theropod dinosaur (12) Atreipus spp. ornithischian dinosaur (13) ornithischian dinosaur (14)

2 Supplementary Material 2 Supplementary Materials: Table 2: Ages and localities for Figure 2 of paper and Figures 1 and 2 of supplementary materials. na, indicates that although many tracks are known from the locality and are in various institutions, we have not attempted to quantify their numbers for this study; Maximum size is based on a survey of the largest of the specimens ( 15 ). Ichnotaxa age Ma Formation Abbrev -iation 199 Portland 1 Hartford Stony Brook, Kelsey Furguson Quarry, Simsbury, CT Basin Locality Age Ichnotaxa #Non-Dinosaur Tracks Hettangian- Batrachopus deweyii, Sinemurian Otozoum moodii, #Dinosaur Tracks %Dinosaur Tracks Max. Theropod Track Size #Non Dinosaur Taxa #Dinosaur Taxa %Dinosaur Taxa na na na (16) Comments 199 McCoy Brook 2 Fundy Five Islands Provincial Park, Blue Sac shore Hettangian- Batrachopus deweyii, Sinemurian Batrachopus gracilis,, Otozoum moodii 200 Portland 3 Hartford Chicopee, MA Hettangian- Batrachopus deweyii, Sinemurian 200 Turners Falls 200 Turners Falls 4 Deerfield Stoughton Quarry, Montague, MA 5 Deerfield Barton Cove, Lily Pond, Gill, MA 201 Portland 6 Hartford Portland brownstone Quarry, Portland, CT 201 Boonton 7 Newark Boonton Dam, Boonton, NJ Hettangian Batrachopus deweyii, Batrachopus gracilis, Eubrontes giganteus Hettangian Batrachopus deweyii, Batrachopus gracilis, Hettangian Batrachopus deweyii,, Otozoum moodii Hettangian Batrachopus deweyii, na na na (14,27) na na na (revised from ref. 17) na na na (revised from ref. 17,) na na na (revised from ref. 17) na na na (revised from ref. 17) youngest Newark basin assemblage (16)

3 Supplementary Material Towaco 8 Newark Riker Hill Quarry, Roseland, NJ 201 Towaco 9 Newark Stephen Drive, Montville, NJ Hettangian Ameghinichnus n. sp., Batrachopus deweyii, Hettangian Anchisauripus tuberosus the most densely sampled locality in Newark basin (17) LA Rhynchosauroides (16) 201 East Berlin and lower Turners Falls 10 Hartford Hettangian Batrachopus deweyii, 201 Towaco 11 Newark Vreeland Quarry, Montville, NJ 201 Towaco 12 Newark Toms Point, Lincoln Park, NJ 201 Feltville 13 Newark Shrump Quarry, Roseland, NJ 201 Turkey Run 14 Culpeper Oak Hill Estate, Aldie, VA 201 Feltville 15 Newark Exeter Golf Course, Exeter, PA 201 McCoy Brook 201 Shuttle Meadow Hettangian Batrachopus deweyii, Hettangian Batrachopus deweyii, Hettangian Batrachopus deweyii, Hettangian cf. Hettangian Grallator cf. G. parallelus, Anchisauripus tuberosus, Eubrontes giganteus 16 Fundy Wasson Bluff Hettangian Batrachopus deweyii,, Otozoum moodii 17 Hartford Hettangian Batrachopus deweyii, Eubrontes giganteus na na na (revised from ref.17) (16) (16) (16) na na na (27) (16) na na na (27) na na na (revised from ref. 17)

4 Supplementary Material Midland 18 Culpeper Licking Run Reservoir, Midland, VA Hettangian Batrachopus deweyii na na na (16) 201 Feltville 19 Newark Vosseller Rd., Martinsville, NJ Hettangian Eubrontes giganteus oldest interflow assemblage (16) 201 Passaic 20 Newark Exeter Village, Exeter, PA Hettangian Grallator parallelus (16) 201 Passaic 21 Newark R. H. Hamilton Quarry, and Montclair State Univ., Clifton and Paterson, NJ Hettangian Rhynchosauroides n. sp., Batrachopus deweyii, Eubrontes giganteus FA, Eubrontes giganteus; superb specimens of all taxa (16) 202 Passaic 22 Newark Exeter Village, Exeter, PA Batrachopus deweyii, Anchisauripus tuberosus (16) 202 Passaic 23 Newark Exeter Village, Exeter, PA Grallator parallelus (16) 202 Passaic 24 Newark Friendship Home, Exeter, PA 202 Passaic 25 Newark Friendship Home, Exeter, PA 202 Passaic 26 Newark Friendship Home, Exeter, PA Batrachopus gracilis, Apatopus sp.,?brachychirotherium, New taxon B, Grallator parallelus, Anchisauripus tuberosus Grallator parallelus Rhynchosauroides, Batrachopus gracilis, Brachychirotherium, New taxon B, Grallator parallelus, Anchisauripus tuberosus LA, definite Apatopus sp. modified from ref. (18) LA, definite Brachychirotherium (16) very good and abundant Brachychirotherium. Modified from ref. (18)

5 Supplementary Material Passaic 27 Newark Wingspread, Exeter, PA 202 Passaic 28 Newark Type Pine Ridge, Exeter, PA 202 Passaic 29 Newark Pathfinder Meadows, Exeter 202 Passaic 30 Newark Pathfinder Meadows, Exeter Township 202 Passaic 31 Newark West Orange, NJ 204 Passaic 32 Newark Heister's Creek, Exeter Township, PA Gwyneddichnium sp., Batrachopus gracilis, Brachychirotherium, New Taxon B, Grallator parallelus, Anchisauripus tuberosus ~ LA, Gwyneddichnium, very good Anchisauripus tuberosus. Modified from ref. (18) Grallator parallelus (16) Grallator parallelus (16) NewTaxon B,? Grallator parallelus major reptile bone site (26,16) Apatopus sp na (19) New Taxon B,?Gwyneddichnium sp., Grallator parallelus Modified from ref. (8) 204 Passaic 33 Newark Tulpehocken Rd., Exeter Township 204 Passaic 34 Newark Shelbourn Square, Exeter Township, PA 205 Passaic 35 Newark Valley Ridge, Exeter Township, PA Grallator parallelus (16) New Taxon B, Batrachopus gracilis, Grallator parallelus Modified from ref. (8) Grallator parallelus (16) 205 Passaic 36 Newark Fairview Chapel, Exeter Township, PA Rhynchosauroides sp na (16) 206 Passaic 37 Newark Passaic, NJ Procolophonichnium sp.,?gwyneddichnium sp na (19)

6 Supplementary Material Passaic 38 Newark Furnace Hill, Exeter Township, PA 206 Blomidon 39 Fundy Red Head, Rossway, Nova Scotia 207 Passaic 40 Newark Monacacy Hill, Amity Township, PA?? Batrachopus cf. B. gracilis, Chirotherium lulli, Atreipus sp., Grallator parallelus Apatopus cf. A. lineatus, Brachychirotherium, cf. Atreipus sp., Grallator parallelus, Anchisauripus tuberosus Atreipus sp modified from Szajna and Hartline (20) LA C. lulli, LA Atreipus na na na (27) na (16) 208 Passaic 41 Newark Victoria Hill, Amity Township, PA 208 Passaic 42 Newark Douglassville, Amity Township, PA??Norian Apatopus lineatus, New Taxon B, Grallator parallelus, Anchisauripus tuberosus Gwyneddichnium sp.,?batrachopus sp., Atreipus sp., Grallator parallelus FA Batrachopus cf. B. gracilis (16) modified from ref. (8) 209 Balls Bluff 43 Culpeper Floris, VA Norian Apatopus sp. na na na na (21) 209 Balls Bluff 44 Culpeper Manassas National Park, VA 210 Passaic 45 Newark East Greenville 211 Balls Bluff 46 Culpeper Culpeper Crushed Stone Quarry, Stevensburg. VA Norian Rhynchosauroides sp. na na na na (22) Norian Atreipus sp (16) Norian Brachychirotherium spp.. Anchisauripus sp. na na na (23) 211 Passaic 47 Newark Rutherford, NJ Norian Apatopus sp., unnamed dinosaurian genus 1, Atreipus sp., Anchisauripus tuberosus FA Anchisauripus tuberosus Modified from ref. (13)

7 Supplementary Material Passaic 48 Newark Limrick Airport Business Campus, Limerick, PA Norian Atreipus sp., Grallator parallelus (16) 214 Passaic 49 Newark Sanatoga Commons, Liberty Hill, Sanatoga, PA Norian Gwyneddichnium sp., Atreipus sp (16) 214 Passaic 50 Newark Sanatoga Auto Body Shop, Sanatoga, PA Norian Atreipus sp (16) 215 Passaic 51 Newark Smith-Clark Quarry, Milford, NJ 215 Passaic 52 Newark Sanatoga Quarry, Sanatoga, PA 215 Blomidon 53 Fundy Paddy Island area, Medford, Nova Scotia 216 Passaic 54 Newark Heather Glen, Limerick, PA Norian R. hyperbates, Apatopus lineatus, Chirotherium lulli, Brachychirotherium sp., Atreipus sp., Grallator parallelus, new genus 2 Norian Atreipus acadianus, New Genus 1 Norian R. hyperbates, Apatopus lineatus, Chirotherium lulli, Brachychirotherium, Atreipus, unnamed dinosaurian genus 1 Norian Rhynchosauroides sp, Atreipus sp FA C. lulli. Modified from ref. (13) Modified from ref. (13) na na na na (16) 216 Passaic 55 Newark Graterford Prison, Graterford, PA Norian Atreipus sp Passaic 56 Newark Nishisackawic k Creek, Carno- Norian Atreipus sp Modified from ref. (13)

8 Supplementary Material Passaic 57 Newark Mainland, PA Carno- Norian 217 Passaic 58 Newark Ridge Pike & Township Ln. Rd., Trappe, PA 218 Passaic 59 Newark Blooming Glen Quarry, Blooming Glen, PA 219 Lockatong 60 Newark Upper Fairview, PA Carno- Norian Carnian Carnian Gwyneddichnium sp., Atreipus sp., Grallator parallelus Atreipus sp., Grallator parallelus Apatopus lineatus, Gwyneddichnium sp., Atreipus sp. indt. dinosaur 221 Lockatong 61 Newark Arcola, PA Carnian R. hyperbates, Gwyneddichnium sp., Apatopus sp., Atreipus sp., Grallator parallelus 222 Lockatong 62 Newark Gwynedd, PA Carnian Gwyneddichnium sp.,?atreipus sp. 222 Stockton 63 Newark Grandview and South Nyack, NY 222 Stockton 64 Newark Haverstraw (south), NY 222 Stockton 65 Newark Haverstraw (north), NY Carnian Carnian Carnian Atreipus sp. Grallator parallelus Apatopus sp., Atreipus sp.,?grallator parallelus sp (16) (16) (16) na (16) FA R. hyperbates, Modified from ref. (13) FA Gwyneddichnium (13) (16) FA Grallator parallelus. Modified from ref. (24) FA listed taxa; oldest Newark basin track assemblage? Modified from ref. (24)

9 Supplementary Material 9 Table 2, continued: Osteological Taxa Age Ma Formation Abbreviation Basin Locality Age Osteological Taxon Comments 199 Portland 66 Hartford Hines Quarry, Longmeadow, MA 201 McCoy Brook 67 Fundy Wasson Bluff, Cumberland County, Nova Scotia 202 Passaic 68 Newark Pathfinder Meadows, Exeter Township Sinemurian protosuchian Stegomus longipes type specimen, partial skeleton and skull (17) Hettangian protosuchian Protosuchus micmac Abundant skeleteal elements, site also has produced abundant prosauropod dinosaurs, rare ornithischian and possible theropod dinosaur teeth and bones, and abundant sphenosuchian skeletons and elements, and rare trithelodonts (25) protosuchian Protosuchus sp., Hypsognathus fennerii Protosuchus: osteoderms, jaw, postcranial fragments. Hypsognathus, abundant skulls, partial skeletons and individual bones and teeth (16) 202 Passaic 69 Newark Walnut Street, Exeter phytosauria indet. teeth (16) Township, PA 202 Passaic 70 Newark Clifton, NJ Hypsognathus fennerii type specimen, partial skeleton and mandibles (26) 205 Passaic 71 Newark Passaic, NJ Hypsognathus fennerii several partial skulls and skeletons (26) 206 Passaic 72 Newark Passaic, NJ Hypsognathus fennerii partial skull (26) 206 Blomidon 73 Fundy Red Head, Rossway, Norian- phytosauria indet. rostrum, fragmentary mandible, osteoderm (27) Annapolis Co., Nova Scotia 210 Passaic 74 Newark East Greenville Norian Hypsognathus fennerii partial skull (26) 211 Passaic 75 Newark Hosensack Creek, lower Norian phytosaur: Clepsysaurus teeth, skull and postcranial fragments (28) Milford, PA pennsylvanicus 214 Passaic 76 Newark Sanatoga Auto Body Norian phytosauria indet. postcranial elements and teeth (16) Shop, Sanatoga, PA 215 Passaic 77 Newark Smith-Clark Quarry, Norian phytosauria indet. tooth (16) Milford, NJ 215 Blomidon 78 Fundy Paddy Island area, Medford, Nova Scotia Norian Hypsognathus cf. H. fennerii Complete skull and fragmentary postcranial elements, partial mandible (26) 221 Lockatong 79 Newark Granton Quarry, North Carnian phytosaur, cf. Rutiodon partial juvenile skull (29) Bergen, NJ 222 Stockton 80 Newark Edgewater, NJ Carnian Rutiodon manhattanensis partial postcranial skeleton (30)

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14 Supplementary Material 14 Supplemental Material, Table 3: Concentrations of elements at the four sections shown is Supplemental Material Figure 3 (31,32,33). LOI, represents loss on ignition and corresponds roughly to organic matter content plus water. Depth is depth above (+) or below (-) base of blue-gray sandstone: first number is top of sample, second is bottom. (--), indicates problems with the mechanics of processing the sample (e.g. vial damage). The prefixes 1, 2, 3, and g correspond to samples from sections I, II, III, and Grist Mills sections. Coordinates for localities given in ref. 34. Sample 1TJ-1 1TJ-2 1TJ-3 1TJ-4 1TJ-5 1TJ-6 1TJ-7 1TJ-8 1TJ-9 1TJ-10 1TJ-11 2TJ-12 2TJ-13 2TJ-14 2TJ-15 2TJ-16 2TJ-17 2TJ-18 2TJ-19 Depth (cm) 0,+10 0, -5-5,-10-10,-14-14,-22-22,-34-34,-42-42,51-51,-60-60,-79-79, ,0 0,-9-9,-14-14,-25-25,-35-35,-43-43,-50-50,-56 Ir ppt(35) 97±19 < 80 25±10 96±19 76±17 71±17 40±12 35±12 56± ±9 119±21 103±20 <85 61±15 23±9 73±17 35±12 SiO2 % TiO2 % Al2O3 % Fe2O3 % MnO % < < < < <0.01 MgO % CaO % Na2O % K2O % P2O5 % LOI % TOTAL Sc ppm V ppm Cr ppm Co ppm Ni ppm Cu ppm Zn ppm As ppm Se ppm < Br ppm Rb ppm Sr ppm Y ppm Zr ppm Nb ppm Sb ppm Cs ppm Ba ppm La ppm Ce ppm Nd ppm Sm ppm Eu ppm Gd ppm Tb ppm Tm ppm Yb ppm Lu ppm Hf ppm Ta ppm Ir ppb(36) < 1 < 1 < 2 < 1 < < 1 < 1 < 2 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 2 Au ppb < 5 < < Th ppm U ppm K / U Th / U La / Th Zr / Hf Hf / Ta La / Yb Eu/ Eu*

15 Supplementary Material 15 TABLE 3, CONTINUED: CONCENTRATIONS OF ELEMENTS AT THE FOUR SECTIONS SHOWN IN FIGURE 8 Sample 3TJ-20 3TJ-21 3TJ-22 3TJ-23 3TJ-24 3TJ-25 3TJ-25A gtj-26 gtj-27 gtj-28 gtj-29 gtj-30 gtj-31 gtj-32 gtj-33 gtj-34 gtj-35 gtj-36 Depth (cm) +15,0 0,-5-5,-9-9,-13-13,-22-22,-29-29,-36 +3,0 0,-5-5,-9-9,-21-21,-31-31,-40-40,-47-47,-51-51,-57-57,-62-62,-65 Ir ppt (35) 158±25 285±33 87±18 114±21 34±11 48±14 39±12 60±15 83±18 177±26 113±21 116±21 19±9 83±18 97±19 28± SiO2 % TiO2 % Al2O3 % Fe2O3 % MnO % < <0.01 <0.01 < < <0.01 < < < <0.01 <0.01 MgO % CaO % Na2O % K2O % P2O5 % LOI % TOTAL Sc ppm V ppm Cr ppm Co ppm Ni ppm Cu ppm < Zn ppm As ppm Se ppm < < < Br ppm Rb ppm Sr ppm Y ppm Zr ppm Nb ppm < Sb ppm Cs ppm Ba ppm La ppm Ce ppm Nd ppm Sm ppm Eu ppm Gd ppm Tb ppm Tm ppm Yb ppm Lu ppm Hf ppm Ta ppm Ir ppb (36) < 1 < 1 < < < 1 < 1 < 1 < 1 < 1 < 1 < < 1 < 1 < 1 Au ppb < Th ppm U ppm K / U Th / U La / Th Zr / Hf Hf / Ta La / Yb Eu/ Eu*

16 Supplementary Material 16 Supplemental Material Table 4: Average Ir values for the four sites in Supplemental Material Figure 3 and Table 4 (32). Depth (cm) average IR

17 Supplementary Material 17 Captions for Supplemental Material Supplemental Material Figure 1, Detailed locality information for Figure 1 of paper. Numbers adjacent to ticks at specific stratigraphic levels refer to localities listed in Supplemental Material Table 2. Supplemental Material Figure 2: Detailed sections for footprint localities (numbers), pollen- and spore-producing levels (P), and macrofossil plant localities (M). Numbers for footprint localities refer to Supplemental Material Table 2. Supplemental Material Figure 3: Measured sections for four along strike sections and the average Ir concentrations (34. 35). Data from Supplemental Material Tables 2, 3, and 4. Note that the highest Ir levels tend to be associated with the white-weathering claystone or adjacent coaly unit (Sections 1- III). However, in the Grist Mills section, the highest Ir is within a red claystone under a light gray siltstone. We believe this red claystone correlates with some part of the white claystone in the other sections, but contains hematite because it was formed under a more oxidizing environment, closer to the border fault. In addition, there is another gray claystone lower in the Grist Mills section without an adjacent an Ir anomaly. Because, red units have the lowest organic C content (oxidizing depositional and diagenetic environment) and black units the highest organic C content (reducing depositional and diagenetic environment), it is clear that there is no consistent pattern between the Ir anomaly and redox state of the strata, arguing against a diagenetic origin of the Ir anomaly. Note also that the uppermost Ir maximum in Section I, is within a gray sandstone containing visible clasts of white claystone, and the relatively high Ir levels probably reflect a reworked clast eroded from the underlying white claystone. Supplemental Material Figure 4: Detail and added contextual information for Figure 2 of text showing position detail of boundary section in the Jacksonwald Syncline Composite section as well as correlation to two other Newark basin boundary sections, paleomagnetic polarity data, and footprint and pollen and spore assemblage distribution. Note that new taxon B is the term applied to an unnamed form by (8), and cly, md, and ss, refer to claystone, mudstone, and sandstone, respectively. Average Ir and pollen and spore percentages from Supplemental Material Figure 3. Interval of time represented by Jacksonwald syncline detailed section based on linear extrapolation from the average accumulation rate implied by the astronomical calibration of the Jacksonwald syncline composite section. Correlation throughout the Newark basin is based on the distinctive magnetic polarity and cycle stratigraphy and the basalts.

18 Supplementary Material 18 References and Notes 1. P. E. Olsen, in Field Guide and Proceedings of the Twelfth Annual Meeting of the Geological Association of New Jersey, J. E. B. Baker, Ed. (Geological Association of New Jersey, William Patterson College, Patterson, 1995), pp P. E. Olsen, in Triassic-Jurassic Rifting and the Opening of the Atlantic Ocean, W. Manspeizer, Ed. (Elsevier, Amsterdam, 1988), pp D. Baird, Harvard College Mus. Comp. Zool. Bull. 117, 449 (1957). 4. Based on the relatively large manus, compared to the pes. 5. D. Baird, The Mosasaur 3, 125 (1986). 6. P. E. Olsen, J. Flynn, The Mosasaur 4, 1 (1989). 7. Based on the relatively small manus, radial arrangement of manual phalanges, and coalesced pads on digit IV. 8. S. M. Silvestri, M. J. Szajna, New Mexico Mus. Natural Hist. Sci. Bull. 3, 439 (1993). 9. P. E. Olsen, K. Padian, in The Beginning of the Age of Dinosaurs, K. Padian, Ed. (Cambridge University Press, New York, 1986), pp M. Lockley, A. P. Hunt, Dinosaur Tracks and Other Fossil Footprints of the Western United States (New York, Columbia University Press, 1995). 11. E. C. Rainforth, Geol. Soc. Amer., Abst. Prog. 32, 67 (2000). 12. P. E. Olsen, J. B. Smith, N. G. McDonald, J. Vert. Paleo. 18, 586 (1998). 13. P. E. Olsen, D. Baird, in The Beginning of the Age of Dinosaurs, K. Padian, Ed. (Cambridge University Press, New York, 1986), pp P. E. Olsen, E. C. Rainforth, in The Great Rift Valleys of Pangea in Eastern North America: Volume 2, Sedimentology and Paleontology, P. M. LeTourneau, P. E. Olsen, Eds., (Columbia University Press, New York, in press). 15. We are especially grateful to the many amateur paleontologists who allowed us access to their collections, without which this paper would have been impossible. Most of the Late Triassic age footprint assemblages with quantitative data are in the private collections of M.J.S. and B.W.H. Most of the Clifton locality data are from the collections of Donald Carter, Fred Cassel, and Ken McKim. 16. this paper. 17. R. S. Lull, State Connecticut, State Geol. Nat. Hist. Surv. Bull. 24, 1 (1915). 18. M. J. Szajna, S. M. Silvestri, Mus. Northern Arizona Bull. 60, 275 (1996). 19. D. Baird, The Mosasaur 3, 125 (1986). 20. M. J. Szajna, B. W. Hartline, in The Great Rift Valleys of Pangea in Eastern North America: Volume 2, Sedimentology and Paleontology, P. M. LeTourneau, P. E. Olsen, Eds., (Columbia University Press, New York, in press). 21. N. C. Fraser, pers. comm., P. J. W. Gore, P. J. W. in Triassic-Jurassic Rifting and the Opening of the Atlantic Ocean, W. Manspeizer, Ed. (Elsevier, Amsterdam, 1988), pp , 23. This particular footprint at the Culpeper basin has been termed Kayentapus minor (R. E. Weems, Virginia Div. Min. Res. Pub. 119, 113, (1990)). but is in our view indistinguishable from large Anchisauripus sp. 24. P. E. Olsen, J. Flynn, The Mosasaur 4, 1 (1989). 25. P. E. Olsen, N. H. Shubin, M. E. Anders, Science 237, 1025 (1987). 26. H.-D. Sues, P. E. Olsen, D. M. Scott, P. S. Spencer, J. Vert. Paleo. 20, 275 (2000). 27. P. E. Olsen, R. W. Schlische, P. J. W. Gore, Field Guide to the Tectonics, Stratigraphy, Sedimentology, and Paleontology of the Newark Supergroup, Eastern North America. (International Geological Congress, Guidebooks for Field Trips T351, American Geophysical Union, Washington, D.C., 1989). 28. I. Lea, Jour. Acad. Nat. Sci. Phil. (series 2) 2, 185 (1853). 29. E. H. Colbert, Novitates 2230, 1 (1965).

19 Supplementary Material F. von Huene, Bull. Am. Mus. Nat. Hist. 32, 275 (1913). 31. All analyses by XRF and INAA except as noted. 32. Common datum for averaging is the base of the "blue-gray sandstone" at 0 m. Averaging performed by interpolated Ir values to common depth scale, in 1 cm increments in columns and then averaging across equal depths in rows. 33. Material consisted of channel samples ( i.e. contiguous, continuously sampled intervals) covering an average of 3 cm. Samples were manually crushed in plastic wrap, then mechanically in an alumina (ceramic) jaw crusher, and powdered using an automatic agate mill. Analyses for major and selected trace elements was done by standard X-ray fluorescence spectrometry (XRF) procedures (for information on standards, procedures, accuracy and precision, see W. U. Reimold, C. Koeberl, J. Bishop, Geochim. Cosmochim. Acta, 58, 2689, 1994). The rest of the elements, except the ICS Ir (see ref. 36), were measured using instrumental neutron activation analysis (INAA). For details on the method, instrumentation, procedures, standards, data reduction, accuracy, precision, etc., see C. Koeberl, J. Radioanalytic. Nuclear Chem., 168, 47 (1993). Samples were irradiated at the TRIGA Mark II type reactor at the Atominstitut der Österreichischen Universitäten in Vienna for 7 hours at a flux of about 2 x ncm -2 s Section I, lat , long ; Section II, lat , long ; Section III, lat , long ; Grist Mills, lat , long Ir content was measured with the ICS (iridium coincidence spectrometry) system at the Institute of Geochemistry at the University of Vienna. Crushed and powdered samples of about 50 mg each, as well as standards, were sealed into high purity quartz glass tubes, packed into aluminum foil and an aluminum capsule, and irradiated for 24 to 48 at a flux of about 7 x 1013 ncm-2s-1. After a cooling period of about ten weeks, the samples were first measured for five to eight hours. The lines of 192Ir at 316 and 468 kev were used, and the method requires that only coincident signals at both lines are used for further processing. Samples that yielded results close to the detection limit (ca. 5 ppt) were measured for at least another 24 hours. The precision of the Ir measurements follows a logarithmic error function with the lowest relative errors in the highest concentrations (e.g., 21±9 ppt vs. 285±33 ppt). For details on this method (standards, instrumentation, data reduction, precision, accuracy, etc.), see C. Koeberl, and H. Huber, J. Radioanalytic. Nuclear Chem., 244, 655. (2000). 36. INAA data for Ir have detection limits of 1-2 ppb and are hence not reliable.